Built in 1869 by the East London Railway Company, which reused the Thames Tunnel intended for horse-drawn carriages, the line became part of the London Underground network in 1933. Description from snipview.com. I searched for this on bing.com/images
GOOD EXAMPLE From what I've gather this piece has a creative feature of displaying the location of the gallery while mimicking the artist medium that you can expect to see when you attend this exhibition gallery. However I should have liked to see more text in that empty space that reinforces this concept without a viewer speculating at what the design is.